Locking device for secure, repeatable readings: once you set the measurement position, it stays fixed to prevent drift during use, improving consistency across measurements. Precision machined design for easy reading: the tool is built with tight tolerances and a clean construction that makes the scale easy to read and operation straightforward. Alloy measuring heads for versatile internal size measurement: suitable for a range of internal dimensions, with fine workmanship and burr surfaces to ensure smooth insertion and accurate contact. Builtin ratchet stop for accurate repetitive readings: the ratchet mechanism provides consistent force and repeatable results, ideal for QC checks and batch inspections. Calibration ring and adjustment tool included: a calibration ring allows precise zeroing, and a small wrench is provided for easy adjustments to maintain accuracy over time. Robust, durable construction for workshop use: designed to withstand daily use in manufacturing, , and quality control environments while maintaining reliable performance. Clear specifications at a glance: alloy measuring heads, locking device, builtin ratchet stop, calibration ring, and included small wrench for adjustments. Compatible applications: internal diameter measurement in a variety of parts where precise bore or hole sizes matter, such as housings, flanges, and fixtures. Practical use scenarios: Automotive and engine work: verify inner bore dimensions in engine blocks, cylinders, or transmission housings during assembly or overhaul. Machinery and manufacturing: check internal bores on machine parts, sleeves, or fixtures to ensure proper fit and alignment. Quality control and inspection: perform repeatable checks of internal sizes on produced parts to confirm they meet tolerance requirements. Key benefits summary: improves measurement accuracy with a secure locking mechanism, provides easytoread and precise readings due to its machined construction, supports versatile internal size measurements with burr alloy heads, ensures repeatable results with a builtin ratchet stop, and offers straightforward calibration and maintenance with a dedicated ring and wrench.